Process of dyeing polyethylene terephthalate fiber



dampe United States Patent PROCESS OF DYEING POLYETHYLENE TEREPHTHALATE FIBER No Drawing. Application December 27, 1951,

I 7.. Serial No. 263,693

6 Claims. (Cl. 8-46) This invention relates to a process for dyeing polyethylene terephthalate fiber. It is an object of this invention to provide a process for producing black to navy-blue shades on the mentioned fiber by developing thereon azoic colors. A further object is to develop an improved process for the aforegoing purposes which is free of tarring troubles in the application and which produces strong dyeings of good fastness qualities. Additional objects and achievements of this invention will become apparent as the description proceeds.

British Patent No. 629,452 discloses a process for coloring polyester fibers by applying thereto a diazotizable amine and a coupling component together, in the absence of any swelling agents, and subsequently treating the fiber with aqueous nitrous acid at a temperature of about 85 C., to effect simultaneously diazotization and coupling. Subsequent experience has shown, however, that this process is not applicable to the production of black and navy-blue shades. Thus, it is well known that these shades require as diazotizable amine an azo-diaryldiamine, for instance a compound of the formula set forth hereinbelow, and it has been observed that the dyeing in such cases, if efiected according to the aforesaid British patent is usually attended by considerable tarring (Waters, J. Soc. of Dyers and Colourists, vol. 66, page 614). This not only contaminates the vessel employed and clogs its channels and valves, but also contaminates the dyed fiber and produces dyeings weak to crocking.

Now according to my invention, the aforesaid troubles are surprisingly eliminated, by conducting the impregnation of the fiber in two distinct steps. In the first step, the fiber is impregnated with an aqueous suspension of the requisite azo-diaryl-diamine. Following this step, the fabric is rinsed thoroughly to remove any loosely adhering diamine (and carrier, if any was used) and is impregnated with an aqueous dispersion of.2,3-hydroxynaphthoic acid, whereupon the fiber. is subjected to the action of nitrous acid.

The first impregnation'is effected at a temperature preferably above 185 F. Thus, this impregnation may be carried out in a closed vessel at a convenient temperature, say, up to 275 F. If the temperature employed is not very high, say if the temperature is in the range of 185 F. to 225 F., a carrier is preferably added, for instance oor p-phenyl phenol. The carrier is partly absorbed by the fiber, while the remainder is washed out in the mentioned rinsing step.

In the second step, the impregnation with 2,3-hydroxynaphthoic acid may likewise be carried out in an open or closed vessel in the range of temperatures above indicated, but a carrier is no longer needed.

The treatment with nitrous acid is effected from aqueous solution and is again preferably carried out at a tem perature above 185 F and ordinarily in a closed vessel, to prevent the escape of nitrous acid.

As azo-diaryl-diamine for the first step, may be employed a compound having two aromatic nuclei joined together by an azo bridge and bearing each a primary amino 2:27am Patented Dec. 20, 1955 group in position para to the azo bridge. More particularly, the diamine may be expressed by the formula wherein X and Y each stand for hydrogen or methyl, while R--NH2 designates the radical of a customary arylamine-type coupling component, for instance aniline, toluidine, alpha-naphthylamine and cresidine (S-methyl- 2-methoxy-aniline) The quantity of this compound applied to the fiber may be anywhere from 0.5% to 5% by weight based on the weight of the fiber, depending on the depth of shade desired in the finished fiber. To assist in the dispersion of this compound in the aqueous bath, any common dispersing agent may be employed, for instance isopropyl naphthalene-sodium sulfonate. The quantity of this agent is preferably about 0.25% by weight based on the weight of the fiber.

The 2,3-hydroxy-naphthoic acid may likewise be dispersed in its aqueous bath by the aid of the same or a different dispersing agent. Certain commercial preparations of this coupling component contain a dispersing agent and require no further addition of such an agent. The quantity of this coupling component may be anywhere from 1.5% to 12% by Weight based on the weight of the fiber, again depending on the strength of shade sought to be produced. Although theoretically one mole of the diazotizable diamine will require two moles of the coupling component, their mutual ratio may be varied within limits, say from 1 to 3 unit weights of the coupling component for each unit weight of the diamine.

In addition to overcoming the difliculties of tarring, my novel process produces stronger shades with less dyestuff, and the dyeings are faster to light, laundering, rubbing and dry cleaning than those obtainable by other methods heretofore suggested in the art. My process has the further advantage of being commercially attractive from an economical standpoint, since dyeings can be produced at much lower cost than is possible with the customary, dispersed acetate dyestuffs.

Without limiting my invention, the following examples are given to illustrate my preferred mode of operation. Parts mentioned are by weight.

Example 1 15 parts of fabric woven from polyethylene terephthalate staple yarn were immersed in a dye beck containing 500 parts of water and the liquor was then heated to F. A mixture of 0.80 part of a commercial azo-diaryldiamine (see below) and 0.3 part of a sodium alkyl-aryl sulfonate (defined below), pasted together with a small quantity of hot water, was added. 1.25 parts of p-phenyl phenol were then added, whereupon the mass was heated up and boiled for 1.5 hours. The fabric was then rinsed thoroughly, first with cold water and then with warm water (120 F.).

The dye beck containing the fabric was then filled with 0.4 part of a standard 2,3-hydroxynaphthoic acid powder (containing a dispersing agent) in 500 parts of water. The bath was then heated up and boiled for one hour, after which the bath was drained, and 500 parts of water containing 1.5 parts of sodium nitrite were entered. A dilute sulfuric acid solution containing 3.0 parts of H250; was then added and the temperature of the bath was raised and held at F. for 0.5 hour. Finally, the bath was drained and the fabric was rinsed with water and dried.

No tarring troubles duringdyeing were experienced,

and the resulting dyeing was a good black of excellent fastness properties.

The azo-diaryl-diamine mentioned hereiuabove was a standardized commercial powder, containing 65% of a diluent (dextrin) and 35% of the compound obtained by coupling p-nitro-aniline to a-naphthylamine and reducing the nitro group.

The sodium alkyl-aryl sulfonate was a commercial detel-gent consisting essentially of the sodium sulfonate of dodecyl benzene and homologous alkylated benzenes.

Example 2 Fifty parts of fabric woven from polyethylene terephthalate filament yarn were immersed in a small laboratory jig containing 3000 parts of water and the liquor was then heated to 120 F. A mixture of 3.75 parts of the amdiaryl-diamine defined in Example 1 and 1.0 part of a sodium alkyl-aryl sulfonate, pasted together with a small quantity of hot water, was added. 7.50 parts of paraphenylphenol were then added, whereupon the temperature was raised to the boil and the fabric was worked at this temperature for two hours. The bath was then drained and the fabric was rinsed thoroughly with water. The jig was filled with a fresh bath containing 2.5 parts of a standard 2,3-hydroxynaphthoic acid powder in 3000 parts of water. The bath was heated to the boil and the fabric was worked at this temperature for 0.5 hour after which the bath was drained and the fabric was again rinsed thoroughly. The fabric was then diazotized at the boil in a fresh bath containing 5.0 parts of sodium nitrite, 10 parts of sulfuric acid and 3000 parts of water for one-half hour. Finally, the bath was drained and the fabric was scoured in a fresh bath containing 1.5 parts each of NaOH and a long-chain fatty alcohol sulfate and 3000 parts of water. The fabric was then rinsed with water and dried. A good black having excellent fastness was obtained.

Example 3 A one-pound package of polyethylene terephthalate fiber in the form of top was loaded into a Smith-Drum package dyer and wet out with water. 0.05 lb. of the dyestuff described in Example 1 and 0.02 lb. of paraphenylphenol was added at 110 F. Water was added to bring the volume of 4 liters. The temperature was raised to 205 F. and the liquor was circulated through the package at this temperature for one hour. The bath was t 1.31! dropped and the package was rinsed with water. 0.025 lb. of 2,3-hydroxynaphthoic acid powder was then applied for one hour at 205 F. and the package was rinsed with water. 0.1 lb. of sodium nitrite was added at 80 F. in a fresh bath and circulated at this temperature for 5 minutes. After addition of 0.2 lb. of sulfuric acid, the temperature was raised to 205 F. and held 0.5 hour to elfect diazotization.

A level, well penetrated black shade having excellent fastness was obtained.

Example 4 8.0 parts of fabric woven from polyethylene terephthalate staple yarn were immersed in a dye beck containing 480 parts of water and the liquor was then heated to 120 F. A mixture of 0.4 part of a commercial azodiaryl-diamine (see below) and 0.16 part of a sodium alkyl-aryl sulfonate (same as in Example 1), pasted joint- 13/ with a small quantity of hot water, was added. 1.0 part of p-phenylphenol was then added, whereupon the mass was heated up and boiled for 2.0 hours. The fabric was then rinsed thoroughly, first with cold water and then with warm water (120 F.).

The dye beck containing the fabric was then filled with a dispersion of 0.2 part of a standard 2,3-hydroxynaphthoic acid powder (containing a dispersing agent) in 480 parts of water. The bath was heated up and boiled for one hour, after which it was drained and 480 parts of water containing 0.8 part of sodium nitrite were entered. A dilute sulfuric acid solution containing 1.6 parts of sulfuric acid was then added, and the temperature of the bath was raised and held at 190 F. for 0.5 hour. Finally, the bath was drained and the fabric was rinsed with water and dried.

No tarring troubles during dyeing were experienced, and the resulting dyeing was a good navy-b1ue shade of excellent fastness properties.

The azo-diaryl-diamine mentioned hereinabove was a standardized commercial powder, containing 82% of a diluent (dextrin) and 18% of the compound obtained by coupling p-nitro-aniline to cresidine and reducing the nitro group. '5

Example 5 A one-pound package of staple yarn was wet out for 10 minutes at 180 F. with water and rinsed. 0.05 pound of the color described in Example 1 was wet out with 0.02 pound of a sodium alkyl-aryl sulfonate and added to a fresh bath at F.; the temperature was raised to 200 F. during 15 minutes; the expansion tank was closed ofi; the temperature was raised further to 250 F. at which value it was held for one hour. After cooling to 200 F., the bath was dropped and the yarn was rinsed and scoured for 10 minutes at F. The yarn was then rinsed and a fresh bath, at 120 F., containing 0.02 lb. of 2,3-hydroxynaphthoic acid was entered and circulated. The temperature was then raised as close to the boil as possible (approximately 200 F.), and the yarn was treated at this temperature for 45 minutes. After rinsing, diazotization was carried out for 30 minutes at 190 F. with 0.1 lb. of sodium nitrite and 0.2 lb. of sulfuric acid. The dyeing had excellent levelness, crockfastness and depth of shade.

When this procedure was repeated with the 2,3-hydroxynaphthoic acid being applied at 250 F., similar excellent results were also obtained.

1 claim as my invention:

1. In the process of dyeing polyethylene terephthalate fiber by treating the fiber with an azo-diaryl-diamine and 2,3-hydroxynaphthoic acid foilowed by diazotization and coupling on the fiber, the improvement which consists of applying the diamine, the naphthoic acid and the nitrous acid in three separate steps in the order named, each of said treatments being made from an aqueous bath at a temperature not less than F., and interposing a rinsing step between the first two treatments, to remove excess diamine from the fiber before it comes in contact with said naphthoic acid compound.

2. A process as in claim 1, wherein the aqueous treatment bath containing the diamine contains further a phenyl-phenol.

3. A process of dyeing polyethylene tcrephthalate fiber,

' which comprises. treating the same with an aqueous bath comprising an azo-diaryl-diamine and a phenyl-phenol at a temperature above 185 F., rinsing the fiber with water to remove loosely held excess amine and phenylphenol, further treating said fiber with an aqueous bath comprising 2,3-hydroxynaphthoic acid at a temperature above 185 F. and then treating the fiber with an aqueous bath comprising nitrous acid, the last'mentioned treatment being effected at a temperature above 185 F.

4. A process as in claim 3, the last-mentioned treatment being effected at a temperature between F. and 212 F.

5. A process of dyeing polyethylene terephthalate fiber, which comprises treating the same in a closed vessel with an aqueous bath comprising an azo-diaryl-diamine at a temperature between 225 F. and 275 F., rinsing the fiber with water to remove loosely held excess diamine, further treating said fiber with an aqueous bath comprising 2,3-hydroxynaphthoic acid at a temperature above 185 F. and then treating the fiber with an aqueous bath comprising nitrous acid, the last-mentioned treatment being effected ata temperature above 185 F 6. A process as in claim 5, wherein the treatment with 2,3-hydroxynaphthoic acid is carried out at a temperature above 200 F.

References Cited in the file of this patent UNITED STATES PATENTS 6 FOREIGN PATENTS Great Britain Oct. 8, 1948 OTHER REFERENCES Du Pont Technical Bulletin for September 1950, pp. 146-154.

Journal Soc. Dyers and Col. for December 1950, pp. 609-613. 

1. IN THE PROCESS OF DYEING POLYETHYLENE TEREPHTHALATE FIBER BY TREATING THE FIBER WITH AN AZO-DIARYL-DIAMINE AND 2,3-HYDROXYNAPHTHOIC ACID FOLLOWED BY DIAZOTIZATION AND COUPLING ON THE FIBER, THE IMPROVEMENT WHICH CONSISTS OF APPLYING THE DIAMINE, THE NAPHTHOIC ACID AND THE NITROUS ACID IN THREE SEPARATE STEPS IN THE ORDER NAMED, EACH OF SAID TREATMENTS BEING MADE FROM AN AQUEOUS BATH AT A TEMPERATURE NOT LESS THAN 185* F., AND INTERPOSING A RINSING STEP BETWEEN THE FIRST TWO TREATMENTS, TO REMOVE EXCESS DIAMINE FROM THE FIBER BEFORE IT COMES IN CONTACT WITH SAID NAPHTHOIC ACID COMPOUND. 